U.S. patent application number 14/806524 was filed with the patent office on 2016-01-28 for method for deammonification process control using ph, specific conductivity, or ammonia.
This patent application is currently assigned to Hampton Roads Sanitation District. The applicant listed for this patent is Hampton Roads Sanitation District. Invention is credited to Charles Bott, Stephanie Klaus.
Application Number | 20160023932 14/806524 |
Document ID | / |
Family ID | 55163729 |
Filed Date | 2016-01-28 |
United States Patent
Application |
20160023932 |
Kind Code |
A1 |
Bott; Charles ; et
al. |
January 28, 2016 |
METHOD FOR DEAMMONIFICATION PROCESS CONTROL USING pH, SPECIFIC
CONDUCTIVITY, OR AMMONIA
Abstract
A method and a system as described herein, including a method
and system of treating ammonium containing water in a
deammonification MBBR process where partial nitritation and
anaerobic ammonium oxidation may occur simultaneously in a biofilm,
or in an integrated fixed film activated sludge process where
partial nitritation takes place in a suspended growth fraction and
anaerobic ammonium oxidation occurs in a biofilm. The method and
system include controlling airflow to the reactor to achieve a
target pH, a target alkalinity, a target specific conductivity,
and/or a target ammonium concentration in the reactor or in the
effluent.
Inventors: |
Bott; Charles; (Virginia
Beach, VA) ; Klaus; Stephanie; (Virginia Beach,
VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hampton Roads Sanitation District |
Virginia Beach |
VA |
US |
|
|
Assignee: |
Hampton Roads Sanitation
District
Virginia Beach
VA
|
Family ID: |
55163729 |
Appl. No.: |
14/806524 |
Filed: |
July 22, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62028185 |
Jul 23, 2014 |
|
|
|
62085959 |
Dec 1, 2014 |
|
|
|
Current U.S.
Class: |
210/630 |
Current CPC
Class: |
C02F 2101/16 20130101;
Y02W 10/10 20150501; C02F 2209/06 20130101; C02F 2209/22 20130101;
C02F 2209/05 20130101; C02F 2209/14 20130101; C02F 3/105 20130101;
Y02W 10/15 20150501; C02F 2209/001 20130101; C02F 3/302 20130101;
C02F 3/006 20130101; C02F 2209/003 20130101; C02F 2209/005
20130101; C02F 2209/38 20130101; C02F 2209/07 20130101; C02F 3/301
20130101 |
International
Class: |
C02F 3/30 20060101
C02F003/30 |
Claims
1. A method of treating ammonium containing water in a wastewater
treatment site, the method comprising: receiving a plurality of
sensor signals, the plurality of sensor signals comprising at least
one of a pH level, an alkalinity level, a specific conductivity
level, and an ammonium concentration level; and controlling flow of
a gas into the wastewater treatment site to meet at least one of a
target specific conductivity level, a target ammonium concentration
level, a target alkalinity level, and a target pH level based on
one or more of the plurality of sensor signals.
2. The method of claim 1, wherein the controlling flow of a gas to
meet the at least one of the target specific conductivity level,
target ammonium concentration level, target alkalinity level, and
target pH level is in a continuous flow moving bed biofilm reactor
in which partial nitritation and anaerobic ammonium oxidation both
occur on a biofilm carrier.
3. The method of claim 1, wherein controlling flow of a gas to meet
the at least one of the target specific conductivity level, target
ammonium concentration level, target alkalinity level, and target
pH level is in a continuous flow integrated fixed film activated
sludge reactor in which partial nitritation occurs in a bulk
suspended biomass fraction and anaerobic ammonium oxidation occurs
on a biofilm carrier.
4. The method of claim 1, further comprising measuring at least one
of the specific conductivity level, ammonium concentration level,
alkalinity level, and pH level in a reactor.
5. The method of claim 1, further comprising measuring at least one
of the specific conductivity level, ammonium concentration level,
alkalinity level, and pH level in the effluent from a reactor.
6. The method of claim 1, wherein the gas comprises air or purified
oxygen or a blend thereof.
7. The method of claim 1, further comprising controlling a gas
valve position based on the at least one of the specific
conductivity level, ammonium concentration level, alkalinity level,
and pH level.
8. The method of claim 1, further comprising controlling a blower
output based on the at least one of the specific conductivity
level, ammonium concentration level, alkalinity level, and pH
level.
9. The method of claim 1, further comprising controlling a gas flow
rate setpoint based on the at least one of the specific
conductivity level, ammonium concentration level, alkalinity level,
and pH level.
10. The method of claim 9, further comprising controlling a valve
position or a blower output based on a gas flow rate setpoint.
11. The method of claim 1, further comprising controlling a
dissolved oxygen setpoint based on the at least one of the specific
conductivity level, ammonium concentration level, alkalinity level,
and pH level.
12. The method of claim 11, further comprising controlling a gas
flow rate setpoint based on the dissolved oxygen setpoint.
13. The method of claim 1, further comprising decreasing the flow
of gas and/or a dissolved oxygen level when the specific
conductivity level is lower than a specific conductivity
setpoint.
14. The method of claim 1, further comprising increasing the flow
of gas and/or a dissolved oxygen level when the specific
conductivity level is higher than a specific conductivity
setpoint.
15. The method of claim 1, further comprising decreasing the flow
of gas and/or a dissolved oxygen level when the ammonium
concentration level is lower than an ammonium concentration
setpoint.
16. The method of claim 1, further comprising increasing the flow
of gas and/or a dissolved oxygen level when the ammonium
concentration level is higher than an ammonium concentration
setpoint.
17. The method of claim 1, further comprising decreasing the flow
of gas and/or a dissolved oxygen level when the pH level is lower
than a pH setpoint.
18. The method of claim 1, further comprising increasing the flow
of gas and/or a dissolved oxygen level when the pH level is higher
than a pH setpoint.
19. The method of claim 1, further comprising decreasing the flow
of gas and/or a dissolved oxygen level when the alkalinity level is
lower than an alkalinity setpoint.
20. The method of claim 1, further comprising increasing the flow
of gas and/or a dissolved oxygen level when the alkalinity level is
higher than an alkalinity setpoint.
21. The method claim 1, the controlling of flow of the gas
comprising an appropriately tuned proportional, a
proportional-integral, a proportional-integral-derivative, or a
logic-based process.
22. The method of claim 1, further comprising measuring nitrate and
ammonia in an influent and in an effluent to determine a nitrate
production ratio level.
23. The method of claim 22, wherein the specific conductivity level
is controlled according to a nitrate production ratio setpoint such
that when the nitrate production ratio level is higher than the
nitrate production ratio setpoint the specific conductivity
setpoint is increased.
24. The method of claim 22, wherein the ammonium concentration
level is controlled according to a nitrate production ratio
setpoint such that when the nitrate production ratio level is
higher than the nitrate production ratio setpoint the ammonium
concentration setpoint is increased.
25. The method of claim 22, wherein the pH is controlled according
to the nitrate production ratio setpoint such that when the nitrate
production ratio level is higher than the nitrate production ratio
setpoint the pH setpoint is increased.
26. The method of claim 22, wherein the alkalinity is controlled
according to the nitrate production ratio setpoint such that when
the nitrate production ratio is higher than the nitrate production
ratio setpoint the alkalinity setpoint is increased.
Description
CROSS REFERENCE TO PRIOR APPLICATIONS
[0001] This application claims priority to and the benefit thereof
from U.S. Provisional Patent Application No. 62/028,185, filed Jul.
23, 2014, titled "METHOD FOR DEAMMONIFICATION PROCESS CONTROL USING
pH, SPECIFIC CONDUCTIVITY, OR AMMONIA," and U.S. Provisional Patent
Application No. 62/085,959, filed Dec. 1, 2014, titled "A METHOD
FOR DEAMMONIFICATION PROCESS CONTROL USING pH, SPECIFIC
CONDUCTIVITY, OR AMMONIA," the entireties of which are incorporated
herein by reference and thereby fully set forth herein.
FIELD OF THE DISCLOSURE
[0002] The present disclosure relates to a system and a method for
treating wastewater, or the like.
BACKGROUND OF THE DISCLOSURE
[0003] Deammonification is a two-step process for biological
treatment of ammonium-containing waters which combines partial
nitritation and anaerobic ammonium oxidation (anammox). In the
first step, aerobic ammonium oxidizing bacteria ("AOB") convert
about 50% of the incoming ammonia to nitrite. In the second step,
anaerobic ammonium oxidizing bacteria ("AMX") convert the remaining
ammonium and nitrite to nitrogen gas and a small amount of nitrate.
This reaction can take place in two separate reactors, with partial
nitritation occurring in an aerobic reactor followed by anammox
occurring in an anoxic reactor (see e.g., U.S. Pat. No. 6,485,646
B1), or it can take place in a single reactor. A number of single
reactor configurations exist including upflow granular sludge,
moving bed biofilm reactor (MBBR), and sequencing batch reactor
("SBR") with biomass separation device (see e.g., U.S. Patent
Application Publication No., US2011/0198284 A1). Deammonification
provides an advantage over traditional
nitrification-denitrification in that it consumes 100% less organic
carbon, produces 90% less sludge and consumes 60% less oxygen.
[0004] The deammonification "MBBR"process consists of a
continuously stirred-tank reactor containing buoyant free-moving
plastic biofilm carriers kept in suspension in the bulk liquid by
aeration or mechanical mixing. The conversion of ammonium takes
place in a biofilm attached to the plastic biofilm carriers in
which AOB exist on the exterior of the biofilm, while AMX exist
deeper within the biofilm in an anoxic environment.
[0005] The key parameters for control of this process are influent
flow and dissolved oxygen ("DO") concentration. Flow of water to
the reactor determines the ammonium load on the system as well as
incoming alkalinity. It is desirable to maintain a low dissolved
oxygen concentration (e.g., <2 mg/L) in the reactor to limit the
potential growth of nitrite oxidizing bacteria ("NOB") and to avoid
inhibition of AMX by the diffusion of oxygen into the anoxic zone
of the biofilm. The DO concentration in the reactor is determined
by airflow to the reactor, biological activity in the reactor, and
temperature. Alkalinity is consumed by the bacteria to complete
ammonium oxidation. If the alkalinity consumed by the bacteria is
greater than the influent alkalinity, then the pH in the reactor
will decrease. If alkalinity consumed by the bacteria is less than
the influent alkalinity, then the pH in the reactor will
increase.
[0006] A deammonification MBBR process can be operated with
intermittent aeration. See, e.g., Zubrowska-Sudol, M., Yang, J.,
Trela, J., Plaza, E., "Evaluation of deammonification process
performance at different aeration strategies," published in Water
Science and Technology. 63(6), 1168-1176 (2011); and Ling D.,
"Experience from commissioning of full-scale DeAmmon.TM. plant at
Himmerfiarden (Stockholm)," published in 2nd IWA Specialized
Conference on Nutrient Management in Wastewater Treatment Processes
(2009). However, continuous aeration is preferred due to simplicity
of operation, more accurate readings of online signals, and
elimination of the need for mechanical mixing during non-aerated
phases. Online measurements from probes located in the reactor or
in the effluent can be used for monitoring performance of the
process. This includes some combination of the following probes:
pH, specific conductivity, ammonium concentration, nitrate
concentration, nitrite concentration, or dissolved oxygen
concentration. In addition an air flow meter in combination with an
air flow control valve modulates airflow to the reactor based on
signals from one or more of the aforementioned probes. This could
also be achieved by a dedicated blower that is controlled to
deliver a target air flow rate. The reactor cannot be operated
without some form of aeration control due to the possibility of
over-aeration leading to the accumulation of nitrite which is
irreversibly inhibitory to AMX at high concentrations.
[0007] It is known that pH, conductivity, and DO sensors can be
used to determine the intermittent air ON and OFF cycles in an
intermittently aerated SBR (see, e.g., U.S. Pat. Nos. 7,846,334 B2
and 8,298,422 B2). It is also known that DO based aeration control
can be used in a deammonification MBBR process (see e.g., U.S.
Patent Application Publication No. US2013/0256217 A1 and U.S. Pat.
No. 8,057,673 B2).
[0008] U.S. Pat. No. 7,846,334 B2 describes a method for treating
ammonium-containing water in an intermittently aerated
deammonification SBR in which the length of the aerated and
non-aerated phases is controlled by a low and high pH setpoint. See
also Wett, "Development and implementation of a robust
deammonification process," published in Water Science and
Technology, 56 (7) 81-88 (2007). This method is specific to an
intermittently fed, intermittently aerated SBR with the fluctuation
of the range of pH values being at most 0.05 and the DO
concentration being kept between 0.2 mg/L and 0.4 mg/L.
[0009] U.S. Pat. No. 8,298,422 B2 describes a method for treating
ammonium-containing water in an intermittently aerated
deammonification SBR in which a conductivity and/or DO
concentration in the reactor determines the length of the aerated
and non-aerated phases.
[0010] Joss, A., Siegrist, H., Salzgeber, D., Eugster, J., Konig,
R., Rottermann, K., Burger, S., Fabijan, P., Leumann, S. &
Mohn, J., "Full-scale nitrogen removal from digester liquid with
partial nitritation and anammox in one SBR," published in
Environmental Science & Technology, 43(14), 5301-5306 (2009)
describes a method for treating ammonium-containing water in a
continuously or intermittently aerated deammonification SBR in
which a conductivity or ammonia setpoint determines the end of the
reaction phase of the SBR. In this method the conductivity or
ammonia signal is not controlling the aeration but rather the
length of the overall SBR cycle.
[0011] U.S. Patent Application Publication No. US2013/0256217 A1
describes a method for treating ammonium-containing water in a
deammonification MBBR in which a DO setpoint is periodically
adjusted by the controller based on ammonia removal and nitrate
production ratios in the reactor. The ratios are calculated from
sensor values in the tank and the DO setpoint is incrementally
increased or decreased if the ratios fall outside of an optimal
zone. A goal of this method may be to maximize ammonia removal by
increasing the DO setpoint until an optimal ammonia removal
percentage is met. However this method does not protect against
running out of alkalinity in the reactor resulting in a dramatic
decrease in pH. If the DO concentration setpoint is too high, then
the pH will continue to decrease until all of the incoming
alkalinity is consumed.
[0012] A key to the operation of deammonification reactors is the
inhibition of nitrite oxidizing bacteria ("NOB") that compete with
anammox for substrate and for space within the biofilm. Strategies
for inhibition of NOB include high free ammonia concentration, low
dissolved oxygen concentration, high temperature, and transient
anoxia. The method described in U.S. Patent Application Publication
No. US2013/0256217 A1 aims to limit NOB growth by using a
controller to decrease the DO setpoint when the nitrate production
ratio is above the value that would be expected to be produced by
AMX alone. If nitrate production is higher than 10-15% (indicating
proliferation of NOB), then the process DO is limited in an effort
to control NOB activity at the expense of losing NH4 removal.
[0013] U.S. Pat. No. 8,057,673 B2 describes a method for treating
ammonium containing water in a two-reactor deammonification system
in which partial nitritation takes place in the first reactor and
anammox takes place in the second reactor. The first reactor is
aerated to meet a DO setpoint between 0.5 mg/L and 1 mg/L. The pH
in the first reactor is controlled to be between 7.5 and 8. In this
method, the pH signal is not used to control aeration, but,
instead, it is used to control the pH with the intent of inhibiting
NOB in the aerobic reactor.
[0014] U.S. Pat. No. 8,268,173 B2 describes a method for
controlling aeration in an integrated fixed film activated sludge
("IFAS") process based on DO and ammonia concentration to account
for variations in the amount of nitrifying biomass on the carriers
versus the amount of nitrifying biomass in the mixed liquor. This
method does not refer to a deammonification IFAS process (AOB in
the mixed liquor and AMX on the carriers) but rather a process in
which nitrification (AOB and NOB) takes place on both the carriers
and in the mixed liquor.
SUMMARY OF THE DISCLOSURE
[0015] According to aspects of the disclosure, a method and system
of controlling treating ammonium containing water in a
deammonification MBBR process are provided herein. In the method
and the system, partial nitritation and anaerobic ammonium
oxidation may occur simultaneously in a biofilm, or in an
integrated fixed film activated sludge process (e.g., where partial
nitritation takes place in a suspended growth fraction and
anaerobic ammonium oxidation occurs in a biofilm). The method may
include controlling airflow to the reactor to achieve a target pH,
a target alkalinity, a target specific conductivity, and/or a
target ammonium concentration in the reactor or in the effluent.
The method may also include sensing and monitoring pH, alkalinity,
specific conductivity, and/or ammonium concentration via signals
(e.g., four signals) received from one or more sensors placed in
the reactor and/or effluent.
[0016] In a deammonification MBBR, the ammonium concentration in
the effluent corresponds to a given pH, alkalinity, and specific
conductivity, so the four signals can be used interchangeably. It
is desirable to maintain a constant pH (e.g., ammonium, alkalinity,
and specific conductivity) in the effluent to maintain
near-complete use of influent alkalinity and the lowest possible
ammonium concentration in the effluent. It is difficult to achieve
this using DO control alone due to changes in influent ammonium
concentration and alkalinity and changes in oxygen demand in the
reactor. By controlling aeration based on pH, alkalinity, ammonium,
or specific conductivity the alkalinity consumed in the reactor may
be controlled to nearly equal the alkalinity in the influent,
thereby avoiding the possibility of drastic reductions in pH due to
depletion of alkalinity. Controlling based on pH, alkalinity or
specific conductivity provides an added advantage of measuring and
ensuring residual alkalinity while ammonia does not. Controlling
airflow based on pH, alkalinity, ammonium concentration, or
specific conductivity results in more consistent effluent
characteristics with less operator input than DO based aeration
control, as well as avoids problems associated with ammonium being
removed to levels that result in AOB or anammox activity
limitations, and the subsequent induction of NOB growth. Use of pH
or specific conductivity probes also gives the advantage of using a
robust sensor for control.
[0017] In each of a plurality of control modes, the pH, alkalinity,
specific conductivity, or ammonium concentration setpoint(s) can
control the air flow control valve position directly, control the
air flow setpoint which controls the air valve position, or control
the dissolved oxygen setpoint which controls the air flow setpoint
which control the air valve position (cascade control). The control
is accomplished with an appropriately tuned proportional,
proportional-integral, proportional-integral-derivative, or
logic-based algorithm.
[0018] If NOB growth does occur, resulting in an increase in
effluent nitrate, the pH, alkalinity, specific conductivity, or
ammonium concentration setpoints are increased (decreasing the
airflow rate) until the nitrate production ratio is less than the
value that would be expected to be produced by AMX alone (10-15%).
The nitrate production ratio may be defined by the following
equation:
NO 3 production ratio = Effluent NO 3 - Influent NO 3 Influent NH 4
- Effluent NH 4 .times. 100 ( Equation 1 ) ##EQU00001##
[0019] According to an aspect of the disclosure, a method of
treating ammonium containing water in a wastewater treatment site
is provided herein. The method comprises receiving a plurality of
sensor signals, the plurality of sensor signals comprising at least
one of a pH level, an alkalinity level, a specific conductivity
level, and an ammonium concentration level; and controlling flow of
a gas into the wastewater treatment site to meet at least one of a
target specific conductivity level, a target ammonium concentration
level, a target alkalinity level, and a target pH level based on
one or more of the plurality of sensor signals. The controlling
flow of a gas to meet the at least one of the target specific
conductivity level, target ammonium concentration level, target
alkalinity level, and target pH level can be in a continuous flow
moving bed biofilm reactor in which partial nitritation and
anaerobic ammonium oxidation both occur on a biofilm carrier. The
controlling flow of a gas to meet the at least one of the target
specific conductivity level, target ammonium concentration level,
target alkalinity level, and target pH level can be in a continuous
flow integrated fixed film activated sludge reactor in which
partial nitritation occurs in a bulk suspended biomass fraction and
anaerobic ammonium oxidation occurs on a biofilm carrier.
[0020] The method may further comprise measuring at least one of
the specific conductivity level, ammonium concentration level,
alkalinity level, and pH level in a reactor.
[0021] The method may further comprise measuring at least one of
the specific conductivity level, ammonium concentration level,
alkalinity level, and pH level in the effluent from a reactor.
[0022] The gas may comprise air or purified oxygen or a blend
thereof.
[0023] The method may further comprise controlling a gas valve
position based on the at least one of the specific conductivity
level, ammonium concentration level, alkalinity level, and pH
level.
[0024] The method may further comprise controlling a blower output
based on the at least one of the specific conductivity level,
ammonium concentration level, alkalinity level, and pH level.
[0025] The method may further comprise controlling a gas flow rate
setpoint based on the at least one of the specific conductivity
level, ammonium concentration level, alkalinity level, and pH
level.
[0026] The method may further comprise controlling a valve position
or a blower output based on a gas flow rate setpoint.
[0027] The method may further comprise controlling a dissolved
oxygen setpoint based on the at least one of the specific
conductivity level, ammonium concentration level, alkalinity level,
and pH level.
[0028] The method may further comprise controlling a gas flow rate
setpoint based on the dissolved oxygen setpoint.
[0029] The method may further comprise decreasing the flow of gas
and/or a dissolved oxygen level when the specific conductivity
level is lower than a specific conductivity setpoint.
[0030] The method may further comprise increasing the flow of gas
and/or a dissolved oxygen level when the specific conductivity
level is higher than a specific conductivity setpoint.
[0031] The method may further comprise decreasing the flow of gas
and/or a dissolved oxygen level when the ammonium concentration
level is lower than an ammonium concentration setpoint.
[0032] The method may further comprise increasing the flow of gas
and/or a dissolved oxygen level when the ammonium concentration
level is higher than an ammonium concentration setpoint.
[0033] The method may further comprise decreasing the flow of gas
and/or a dissolved oxygen level when the pH level is lower than a
pH setpoint.
[0034] The method may further comprise increasing the flow of gas
and/or a dissolved oxygen level when the pH level is higher than a
pH setpoint.
[0035] The method may further comprise decreasing the flow of gas
and/or a dissolved oxygen level when the alkalinity level is lower
than an alkalinity setpoint.
[0036] The method may further comprise increasing the flow of gas
and/or a dissolved oxygen level when the alkalinity level is higher
than an alkalinity setpoint.
[0037] The controlling of flow of the gas may comprise an
appropriately tuned proportional, a proportional-integral, a
proportional-integral-derivative, or a logic-based process.
[0038] The method may further comprise measuring nitrate and
ammonia in an influent and in an effluent to determine a nitrate
production ratio level.
[0039] The specific conductivity level may be controlled according
to a nitrate production ratio setpoint such that when the nitrate
production ratio level is higher than the nitrate production ratio
setpoint the specific conductivity setpoint is increased.
[0040] The ammonium concentration level may be controlled according
to a nitrate roduction ratio setpoint such that when the nitrate
production ratio level is higher than the nitrate production ratio
setpoint the ammonium concentration setpoint is increased.
[0041] The pH may be controlled according to the nitrate production
ratio setpoint such that when the nitrate production ratio level is
higher than the nitrate production ratio setpoint the pH setpoint
is increased.
[0042] The alkalinity may be controlled according to the nitrate
production ratio setpoint such that when the nitrate production
ratio is higher than the nitrate production ratio setpoint the
alkalinity setpoint is increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] FIG. 1 shows a cross-sectional view of an example of a
specific conductivity (SC) control system for controlling treating
ammonium containing water in a deammonification MBBR process in
which partial nitritation and anaerobic ammonium oxidation occur
simultaneously, constructed according to the principles of the
disclosure.
[0044] FIG. 2 shows a cross-sectional view of an example of an
expanded SC control system, constructed according to the principles
of the disclosure.
[0045] FIG. 3 shows an example of a method of controlling a gas
valve position or a blower output based on a specific conductivity,
according to the principles of the disclosure.
[0046] FIG. 4 shows an example of a method controlling a gas flow
rate setpoint based on specific conductivity, wherein the gas flow
rate setpoint controls a valve position or a blower output,
according to the principles of the disclosure.
[0047] FIG. 5 shows an example of a method of controlling a DO
setpoint based on specific conductivity, wherein the DO setpoint
controls a gas flow rate setpoint that controls a gas flow valve
position or a blower output, according to the principles of the
disclosure.
[0048] FIG. 6 shows a cross-sectional view of an example of an
ammonium concentration ("AC") control system for controlling
treating ammonium containing water in a deammonification MBBR
process in which partial nitritation and anaerobic ammonium
oxidation occur simultaneously, constructed according to the
principles of the disclosure.
[0049] FIG. 7 shows a cross-sectional view of an example of an
expanded AC control system, constructed according to the principles
of the disclosure.
[0050] FIG. 8 shows an example of a method of controlling a gas
valve position or a blower output based on an ammonium
concentration, according to the principles of the disclosure.
[0051] FIG. 9 shows an example of a method controlling a gas flow
rate setpoint based on ammonium concentration, wherein the gas flow
rate setpoint controls a valve position or a blower output,
according to the principles of the disclosure.
[0052] FIG. 10 shows an example of a method of controlling a DO
setpoint based on ammonium concentration, wherein the DO setpoint
controls a gas flow rate setpoint that controls a gas valve
position or a blower output, according to the principles of the
disclosure.
[0053] FIG. 11 shows a cross-sectional view of an example of a
pH-based control system for controlling treating ammonium
containing water in a deammonification MBBR process in which
partial nitritation and anaerobic ammonium oxidation occur
simultaneously, constructed according to the principles of the
disclosure.
[0054] FIG. 12 shows a cross-sectional view of an example of an
expanded pH-based control system, constructed according to the
principles of the disclosure.
[0055] FIG. 13 shows an example of a method of controlling a gas
valve position or a blower output based on pH, according to the
principles of the disclosure.
[0056] FIG. 14 shows an example of a method controlling a gas flow
rate setpoint based on pH, wherein the gas flow rate setpoint
controls a valve position or a blower output, according to the
principles of the disclosure.
[0057] FIG. 15 shows an example of a method of controlling a DO
setpoint based on pH, wherein the DO setpoint controls a gas flow
rate setpoint that controls a valve position or a blower output,
according to the principles of the disclosure.
[0058] FIG. 16 is a diagram showing concentrate flow, AFCV
position, gas flow, pH and pH setpoint for the method described in
FIG. 14, wherein pH controls a gas flow rate setpoint which
controls a valve position.
[0059] FIG. 17 is a diagram showing the pH, ammonium, and specific
conductivity signals corresponding to one another and being used
interchangeably to control aeration.
[0060] FIG. 18 is a diagram showing concentrate flow, AFCV
position, gas flow, pH, and pH setpoint for the method described in
FIG. 14, wherein pH controls gas flow rate setpoint which controls
a valve position.
[0061] FIG. 19 is a diagram showing the pH, ammonium, and specific
conductivity signals corresponding to one another and being used
interchangeably to control aeration.
[0062] FIG. 20 shows a cross-sectional view of an example of an
alkalinity-based control system for controlling treating ammonium
containing water in a deammonification MBBR process in which
partial nitritation and anaerobic ammonium oxidation occur
simultaneously, constructed according to the principles of the
disclosure.
[0063] FIG. 21 shows a cross-sectional view of an example of an
expanded alkalinity-based control system, constructed according to
the principles of the disclosure.
[0064] FIG. 22 shows an example of a method of controlling a gas
valve position or a blower output based on alkalinity, according to
the principles of the disclosure.
[0065] FIG. 23 shows an example of a method controlling a gas flow
rate setpoint based on alkalinity, wherein the gas flow rate
setpoint controls a valve position or a blower output, according to
the principles of the disclosure.
[0066] FIG. 24 shows an example of a method of controlling a DO
setpoint based on alkalinity, wherein the DO setpoint controls a
gas flow rate setpoint that controls a valve position or a blower
output, according to the principles of the disclosure.
[0067] FIG. 25 shows an example of pH controlling DO setpoint,
controlling airflow setpoint, controlling air flow control
valve.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0068] The disclosure and the various features and advantageous
details thereof are explained more fully with reference to the
non-limiting embodiments and examples that are described and/or
illustrated in the accompanying drawings and detailed in the
description. It should be noted that the features illustrated in
the drawings are not necessarily drawn to scale, and features of
one embodiment may be employed with other embodiments as the
skilled artisan would recognize, even if not explicitly stated
herein. Descriptions of well-known components and processing
techniques may be omitted so as to not unnecessarily obscure the
embodiments of the disclosure. The examples used herein are
intended merely to facilitate an understanding of ways in which the
disclosure may be practiced and to further enable those of skill in
the art to practice the embodiments of the disclosure. Accordingly,
the examples and embodiments herein should not be construed as
limiting the scope of the disclosure. Moreover, it is noted that
like reference numerals represent similar parts throughout the
several views of the drawings.
[0069] According to an aspect of the disclosure, a method and a
system are provided herein for treating ammonium containing water
in a deammonification MBBR process where partial nitritation and
anaerobic ammonium oxidation may occur simultaneously in a biofilm,
or in an integrated fixed film activated sludge (IFAS) process
where partial nitritation takes place in a suspended growth
fraction and anaerobic ammonium oxidation occurs in a biofilm. The
method and system include, among other things, controlling airflow
to a reactor to achieve a target pH, a target alkalinity, a target
specific conductivity, and/or a target ammonium concentration in
the reactor or in the effluent. According to a non-limiting example
of the instant disclosure, a target pH may be, for example, between
about 6.0 and about 7.0; a target alkalinity may be, for example,
between about 50 mg/L as CaCO.sub.3 and about 350 mg/L as
CaCO.sub.3; a target specific conductivity that is determined based
on the matrix; and a target ammonium concentration may be, for
example, between about 25 mg/L and about 300 mg/L. Further, the
target dissolved oxygen level may be, for example, between about
0.1 mg/L and about 2.0 mg/L. The foregoing ranges of values, as
understood by those skilled in the art, may vary significantly from
the mentioned values, depending on, for example, wastewater
characteristics, ambient conditions, treatment goals of each
individual plant, etc. The target pH, alkalinity, specific
conductivity and ammonium concentration values may be set as the pH
setpoint, alkalinity setpoint, specific conductivity setpoint, and
ammonium concentration setpoint, respectively. The system may
automatically adjust air flow and/or dissolved oxygen levels, as
described herein, so as to achieve one or more of the setpoint
values.
[0070] FIG. 1 shows a cross-sectional view of an example of a
specific conductivity ("SC") control system 100 for controlling
treating ammonium containing water in a deammonification MBBR
process in which partial nitritation and anaerobic ammonium
oxidation may occur simultaneously, constructed according to the
principles of the disclosure. The SC control system 100 comprises a
gas inlet 2, an influent 4 inlet and an effluent outlet 6. The SC
control system 100 further comprises a gas flow meter 10, a gas
flow valve 11, a controller 13, a gas diffuser 14, a plurality of
sensors 15, 16, 21 (shown in FIG. 6), 22 (shown in FIG. 11), 23
(shown in FIG. 20) and a reactor 17.
[0071] The gas inlet 2 is configured to receive a gas (e.g., air,
oxygen, etc.) and supply the gas to the diffusers 14 via a conduit
5. The gas flow in the conduit 5 may be controlled by the gas flow
valve 11. The gas flow meter 10 is configured to measure the gas
flow in the conduit leading to the diffusers 14 and communicate a
gas flow measurement signal to the controller 13 via a
communication link 8. The controller 13 is configured to receive
the gas flow measurement signal and generate a gas flow control
signal, which is sent to the gas flow valve 11 over the
communication link 8 to control the rate of gas flowing through the
conduit 5 to the diffusers 14.
[0072] The gas flow control valve 11 may include, e.g., a
modulating airflow control valve. The gas flow meter 10 may be
located upstream of the gas flow control valve 11 and provide gas
flow rate feedback in the gas flow measurement signal to the
controller 13 through the communication link 8.
[0073] The reactor 17 may include, e.g., a moving bed biofilm
reactor. The sensors 15, 16 may be located in the reactor 17, or
outside of the reactor 17, such as, e.g., in the effluent. The
sensors 15, 16 may include one or more probes in the reactor 17
and/or in the effluent. The plurality of sensors 15, 16 may include
a dissolved oxygen (DO) sensor, a specific conductivity (SC)
sensor, an ammonium concentration sensor (NH4, shown in FIG. 6)
and/or a pH sensor (pH, shown in FIG. 12).
[0074] The DO sensor 15 may be configured to measure the dissolved
oxygen in the mixture in the reactor 17 (and/or effluent) and
provide a DO measurement signal to the controller 13 over a
communication link 9.
[0075] The SC sensor 16 may be configured to measure the specific
conductivity of the mixture in the reactor 17 (and/or effluent) and
provide an SC measurement signal to the controller 13 over the
communication link 9.
[0076] The NH4 sensor 21 (shown in FIGS. 6, 7) may be configured to
measure the ammonium concentration in the reactor 17 (and/or
effluent) and provide an ammonium concentration (AC) measurement
signal to the controller 13 over the communication link 9.
[0077] The pH sensor 22 (shown in FIGS. 11, 12) may be configured
to measure the pH in the reactor 17 (and/or effluent) and provide
pH measurement signal to the controller 13 over the communication
link 9.
[0078] The alkalinity sensor 23 (shown in FIGS. 20, 21) may be
configured to measure the alkalinity in the reactor 17 (and/or
effluent) and provide alkalinity measurement signal to the
controller 13 over the communication link 9.
[0079] As seen in FIG. 1, the diffuser(s) 14 may be located in the
reactor 17, and materials, such as, e.g., plastic biofilm
carrier(s) 12, may be kept in suspension in the reactor 17 by
continuous aeration provided by the diffusers 14. The influent flow
to the reactor 17 may be equal to the effluent flow and the reactor
17 may be completely mixed. While all of the sensors 15, 16, 21,
22, 23 may be implemented simultaneously in the control system 100
(100', 100'', 100''', 100'''', 100''''', 100'''''', 100'''''''),
the following description provides examples of the control system
100 with two sensors, with an understanding that more than two
sensors may be used.
[0080] Referring to FIGS. 1, 6, and 11, the gas flow meter 10 may
provide gas flow rate feedback to the controller 13 in the gas flow
measurement signal supplied on communication link 8; the SC
measurement signal from the specific conductivity sensor 16 may
provide feedback for any of the disclosed specific conductivity
aeration control methods described in FIGS. 3-5, with the option of
using the DO measurement signal from the DO sensor 15 for control;
the AC measurement signal from the ammonium sensor 21 may provide
feedback for any of the disclosed ammonium aeration control methods
described in FIGS. 8-10, with the option of using the DO
measurement signal from the DO sensor 15 for control; the pH
measurement signal from the pH sensor 22 may provide feedback for
any of the disclosed pH aeration control methods described in FIGS.
13-15, with the option of using the signal from the DO sensor 15
for control; and the alkalinity measurement signal from the
alkalinity sensor 23 may provide feedback for any of the disclosed
alkalinity aeration control methods described in FIGS. 22-24, with
the option of using the signal from the DO sensor 15 for
control.
[0081] The control system 100 (100', 100'', 100''', 100'''',
100''''', 100'''''', 100''''''', individually or collectively
referred to as 100) includes controlling gas (e.g. airflow, oxygen
flow, etc.) to the reactor 17 to achieve a target pH, a target
alkalinity, a target specific conductivity, or a target ammonium
concentration in the reactor 17 or in the effluent. In a
deammonification MBBR, the ammonium concentration in the effluent
corresponds to a given pH, alkalinity and/or specific conductivity,
so the plurality of signals (e.g., four signals) can be used
interchangeably.
[0082] The system 100 maintains a constant pH (e.g., alkalinity,
ammonium and specific conductivity) in the effluent to maintain
near-complete use of influent alkalinity and the lowest possible
ammonium concentration in the effluent. (In an embodiment of the
disclosure, pH, alkalinity and SC can be used interchangeably.) It
is difficult to achieve this using DO control alone due to changes
in influent ammonium concentration and alkalinity and changes in
oxygen demand in the reactor. By controlling aeration based on pH,
alkalinity, or specific conductivity, the alkalinity consumed in
the reactor may be set equal to the alkalinity in the influent,
less the need to maintain some residual in the process effluent of
about 25 to 300 mg/L as CaCO.sub.3, avoiding the possibility of
drastic reductions in pH due to depletion of alkalinity. The system
100 may control gas flow based on pH, alkalinity, ammonium
concentration, and/or specific conductivity, resulting in more
consistent effluent characteristics with little or no operator
input. The system 100 avoids problems associated with ammonium
being removed to levels that result in AOB or anammox activity
limitations, and the subsequent induction of NOB growth. The use
of, for example, pH and/or specific conductivity probes in the
system 100 provides the advantage of using a robust sensor for
control.
[0083] In each of a plurality of control modes described herein,
the pH, alkalinity, specific conductivity, or ammonium
concentration setpoint(s) may be used to control the gas flow
control valve 11 position directly, control the air flow setpoint
which controls the gas flow control valve 11 position, or control
the dissolved oxygen setpoint which controls the gas flow setpoint
which controls the gas flow control valve 11 position (cascade
control). The control is accomplished by means of the controller
13, which includes a computer that may include an appropriately
tuned proportional, proportional-integral,
proportional-integral-derivative, or logic-based process (or
algorithm).
[0084] If NOB growth does occur, resulting in an increase in
effluent nitrate, the controller 13 may decrease gas flow rate to
the reactor 17 by increasing the pH, alkalinity, specific
conductivity, or ammonium concentration setpoints until the nitrate
production ratio is less than the value that would be expected to
be produced by AMX alone (e.g., 10-15%). The controller may control
the pH, alkalinity, specific conductivity or ammonium concentration
setpoints to achieve optimal NO3 production ratio values. The
controller 13 may measure the influent and effluent ammonium
concentrations, and, based on the effluent and influent nitrate
concentrations, determine the nitrate production ratio according to
the following equation:
NO 3 production ratio = Effluent NO 3 - Influent NO 3 Influent NH 4
- Effluent NH 4 .times. 100 ( Equation 1 ) ##EQU00002##
[0085] FIG. 2 shows a cross-sectional view of an example of an
expanded SC control system 100', constructed according to the
principles of the disclosure. The expanded SC control system 100'
includes an integrated fixed film activated sludge (IFAS) reactor
20 with the diffusers 14, meter 10, valve 11, specific conductivity
sensor 16, DO sensor 15, clarifier 18 and return activated sludge
19. A material (or biofilm carriers) 12 may be kept in suspension
by continuous aeration provided by the diffusers 14. The material
may include a carrier made of plastic, metal, ceramic, or any other
material that may be suitable for the application. The IFAS
configuration may include biomass suspended in the mixed liquor as
well as biomass on the biofilm carriers 12. The influent flow to
the reactor may be equal to the effluent flow and the reactor may
be completely mixed. Sensors 16 and 15 may be located in the
reactor 20 or in the effluent. Gas flow to the reactor 20 may be
determined by the valve 11 but may also be determined by varying
the output of a blower or compressor. The meter 10 may be located
upstream of the control valve 11 and configured to provide a gas
flow rate feedback (or gas flow measurement signal) to the
controller 13. An SC measurement signal from the specific
conductivity sensor 16 may provide feedback for any of the
disclosed specific conductivity aeration control methods described
in FIGS. 3-5, with the option of using the signal from the DO
sensor 15 for control.
[0086] FIG. 3 shows an example of a method of controlling a gas
valve position or a blower output based on a specific conductivity,
according to the principles of the disclosure. If the specific
conductivity feedback (SC measurement signal) is less than the
specific conductivity setpoint, a
proportional-integrated-derivative ("PID") controller may decrease
the control valve position or blower output to decrease the
volume/rate of gas supplied to the reactor 20 (or 17). If the
specific conductivity feedback is greater than the specific
conductivity setpoint, the PID controller increases the control
valve position or blower output to increase the volume/rate of gas
supplied to the reactor 20 (or 17). The PID controller may include,
e.g., a scalar PID, a multivariable PID ("MPID"), or the like.
[0087] The PID controller may operate according to, e.g., the
following algorithm, where u(t) is the PID controller output and MV
is the manipulated variable:
u ( t ) = MV ( t ) = K p e ( t ) + K i .intg. 0 t e ( .tau. ) .tau.
+ K d t e ( t ) ( Equation 2 ) ##EQU00003##
where K.sub.p is the proportional gain, K.sub.i is the integral
gain, K.sub.d is the derivative gain, SP is the desired variable
value, PV is the measured variable value, e is the error=SP-PV, t
is the time, and is the variable integration from 0 to t.
[0088] The PID controller may be located in the controller 13.
[0089] The controller 13 may include a PID, a tuned-proportional, a
proportional-integral, a logic-based, or the like, tuning process.
The controller 13 may be configured to adjust control parameters
(such as, e.g., proportional band/gain, integral band/reset,
derivative gain/rate, or the like) to obtain optimal performance of
the processes in the MBBR and/or IFAS systems.
[0090] FIG. 4 shows an example of a method controlling a gas flow
rate setpoint based on specific conductivity, wherein the gas flow
rate setpoint controls a valve position or a blower output,
according to the principles of the disclosure. In this example, the
PID controller may include a plurality (e.g., two) PID controllers
in cascade. If the specific conductivity feedback is less than the
specific conductivity setpoint, then the first PID 1 controller
decreases the gas flow rate setpoint and the second PID 2
controller decreases the gas flow control valve position or blower
output, thereby reducing the volume/rate of gas supplied to the
reactor 20 (or 17). If the specific conductivity feedback is
greater than the specific conductivity setpoint, then the PID 1
controller increases the gas flow rate setpoint and the PID 2
controller increases the gas flow control valve position or blower
output to increase the volume/rate of gas supplied to the
reactor.
[0091] FIG. 5 shows an example of a method of controlling a DO
setpoint based on specific conductivity, wherein the DO setpoint
controls a gas flow rate setpoint that controls a gas valve
position or a blower output, according to the principles of the
disclosure. In this example, the PID controller may include, e.g.,
three PID controllers in cascade. If the specific conductivity
feedback is less than the specific conductivity setpoint, then the
first PID 1 controller decreases the DO setpoint, the second PID 2
controller decreases the gas flow rate setpoint, and a third PID 3
controller decreases the gas flow control valve position or blower
output to reduce the volume/rate of gas supplied to the reactor. If
the specific conductivity feedback is greater than the specific
conductivity setpoint, then the PID 1 controller increases the DO
setpoint, the PID 2 controller increases the gas flow rate
setpoint, and the PID 3 controller increases the gas flow control
valve position or blower output to increase the volume/rate of gas
supplied to the reactor.
[0092] FIG. 6 shows a cross-sectional view of an example of an
ammonium concentration (AC) control system 100'' for treating
ammonium containing water in a deammonification MBBR process in
which partial nitritation and anaerobic ammonium oxidation occur
simultaneously, constructed according to the principles of the
disclosure. The system 100'' comprises the reactor 17 with the
diffusers 14, meter 10, control valve 11, ammonium sensor 21, and
DO sensor 15. Biofilm carriers 12 may be kept in suspension by
continuous aeration provided by the diffusers 14. The influent flow
to the reactor may be equal to the effluent flow and the reactor
may be completely mixed. Sensors 21 and 15 may be located in the
reactor or in the effluent. Gas (e.g., air) flow to the rector may
be determined by the control valve 11. The meter 10 may be located
upstream of the control valve 11 and configured to provide gas flow
rate feedback (gas flow measurement signal) to the controller 13.
An AC measurement signal from the ammonium sensor 21 may provide
feedback for any of the disclosed ammonium aeration control methods
described in FIGS. 8-10, with the option of using the DO
measurement signal from the DO sensor 15 for control.
[0093] FIG. 7 shows a cross-sectional view of an example of an
expanded AC control system 100''', constructed according to the
principles of the disclosure. The system 100''' includes the IFAS
reactor 20 with the diffusers 14, meter 10, control valve 11,
ammonium sensor 21, DO sensor 15, clarifier 18 and return activated
sludge 19. Biofilm carriers 12 may be kept in suspension by
continuous aeration provided by the diffusers 14. The IFAS
configuration may include biomass suspended in the mixed liquor as
well as biomass on the biofilm carriers 12. The influent flow to
the reactor may be equal to the effluent flow and the reactor may
be completely mixed. Sensors 21 and 15 may be located in the
reactor or in the effluent. Gas flow to the rector may be
determined by the modulating control valve 11. The meter 10 may be
located upstream of the control valve 11 and configured to provide
gas flow rate feedback to the controller 13. A signal from the
ammonium sensor 21 may provide feedback for any of the disclosed
ammonium aeration control methods described in FIGS. 8-10, with the
option of using the signal from the DO sensor 15 for control.
[0094] FIG. 8 shows an example of a method of controlling a valve
position or a blower output based on an ammonium concentration,
according to the principles of the disclosure. If the ammonium
concentration feedback is less than the ammonium concentration
setpoint, then the PID controller decreases the control valve
position or blower output to reduce the volume/rate of gas supplied
to the reactor. If the ammonium concentration feedback is greater
than the ammonium concentration setpoint, then the PID controller
increases the control valve position or blower output to increase
the volume/rate of gas supplied to the reactor.
[0095] FIG. 9 shows an example of a method controlling a gas flow
rate setpoint based on ammonium concentration, wherein the gas flow
rate setpoint controls a valve position or a blower output,
according to the principles of the disclosure. If the ammonium
concentration feedback is less than the ammonium concentration
setpoint, then the PID 1 controller decreases the gas flow rate
setpoint and the PID 2 controller decreases the gas flow control
valve position or blower output, thereby reducing the volume/rate
of gas supplied to the reactor. If the ammonium concentration
feedback is greater than the ammonium concentration setpoint, then
the PID 1 controller increases the gas flow rate setpoint and the
PID 2 controller increases the gas flow control valve position or
blower output to increase the volume/rate of gas supplied to the
reactor.
[0096] FIG. 10 shows an example of a method of controlling a DO
setpoint based on ammonium concentration, wherein the DO setpoint
controls a gas flow rate setpoint that controls a control valve
position or a blower output, according to the principles of the
disclosure. If ammonium concentration feedback is less than the
ammonium concentration setpoint, then the PID 1 controller
decreases the DO setpoint, the PID 2 controller decreases the gas
flow rate setpoint, and the PID 3 controller decreases the gas flow
control valve position or blower output, thereby reducing the
volume/rate of gas supplied to the reactor. If the ammonium
concentration feedback is greater than the ammonium concentration
setpoint, then the PID 1 controller increases the DO setpoint, the
PID 2 controller increases the gas flow rate setpoint, and the PID
3 controller increases the control valve position or blower output,
thereby increasing the volume/rate of gas supplied to the
reactor.
[0097] FIG. 11 shows a cross-sectional view of an example of a
pH-based control system 100'''' for treating ammonium containing
water in a deammonification MBBR process in which partial
nitritation and anaerobic ammonium oxidation occur simultaneously,
constructed according to the principles of the disclosure. The
system 100'''' comprises the reactor 17 with the air diffusers 14,
meter 10, control valve 11, pH sensor 22, and DO sensor 15. Biofilm
carriers 12 may be kept in suspension by continuous aeration
provided by the diffusers 14. The influent flow to the reactor may
be equal to the effluent flow and the reactor may be completely
mixed. Sensors 22 and 15 may be located in the reactor or in the
effluent. Gas flow to the reactor may be determined by the control
valve 11. The meter 10 may be located upstream of the control valve
11 and configured to provide gas flow rate feedback to the
controller 13. A signal from the pH sensor 22 may provide feedback
for any of the disclosed pH aeration control methods described in
FIGS. 13-15, with the option of using the signal from the DO sensor
15 for control.
[0098] FIG. 12 shows a cross-sectional view of an example of an
expanded pH-based control system 100''''', constructed according to
the principles of the disclosure. The system 100''''' includes the
IFAS reactor 20 with the diffusers 14, meter 10, control valve 11,
pH sensor 22, DO sensor 15, clarifier 18 and return activated
sludge 19. Biofilm carriers 12 may be kept in suspension by
continuous aeration provided by the diffusers 14. The IFAS
configuration includes biomass suspended in the mixed liquor as
well as biomass on the biofilm carriers 12. The influent flow to
the reactor may be equal to the effluent flow and the reactor may
be completely mixed. Sensors 22 and 15 may be located in the
reactor or in the effluent. Gas flow to the reactor may be
determined by the control valve 11. The meter 10 may be located
upstream of the control valve 11 and configured to provide gas flow
rate feedback to the controller 13. A signal from the pH sensor 22
may provide feedback for any of the disclosed pH aeration control
methods described in FIGS. 13-15, with the option of using the
signal from the DO sensor 15 for control.
[0099] FIG. 13 shows an example of a method of controlling a gas
valve position or a blower output based on pH, according to the
principles of the disclosure. If the pH feedback is less than the
pH setpoint, then the PID controller decreases the control valve
position or blower output to decrease the volume/rate of gas
supplied to the reactor. If the pH feedback is greater than the pH
setpoint, then the PID controller increases the control valve
position or blower output to increase the volume/rate of gas
supplied to the reactor.
[0100] FIG. 14 shows an example of a method controlling a gas flow
rate setpoint based on pH, wherein the gas flow rate setpoint
controls a valve position or a blower output, according to the
principles of the disclosure. If the pH feedback is less than the
pH setpoint, then the PID 1 controller decreases the gas flow rate
setpoint and the PID 2 controller decreases the control valve
position or blower output to decrease the volume/rate of gas
supplied to the reactor. If the pH feedback is greater than the pH
setpoint, then the PID 1 controller increases the gas flow rate
setpoint and the PID 2 controller increases the control valve
position or blower output to increase the volume/rate of gas
supplied to the reactor.
[0101] FIG. 15 shows an example of a method of controlling a DO
setpoint based on pH, wherein the DO setpoint controls a gas flow
rate setpoint that controls a valve position or a blower output,
according to the principles of the disclosure. If pH feedback is
less than the pH setpoint, then the PID 1 controller decreases the
DO setpoint, the PID 2 controller decreases the gas flow rate
setpoint, and the PID 3 controller decreases the control valve
position or blower output to decrease the volume/rate of gas
supplied to the reactor. If the pH feedback is greater than the pH
setpoint, then the PID 1 controller increases the DO setpoint, the
PID 2 controller increases the gas flow rate setpoint, and the PID
3 controller increases the control valve position or blower output
to increase the volume/rate of gas supplied to the reactor.
[0102] FIG. 16 is a diagram showing concentrate flow, AFCV
position, gas flow, pH and pH setpoint for the method described in
FIG. 14, wherein pH controls gas flow rate setpoint which controls
gas valve position. The figure shows the response of the controller
to a disturbance created by a change in pH setpoint. As seen, the
controller adjusts the gas flow setpoint to meet the new pH
setpoint.
[0103] FIG. 17 shows that the pH, ammonium, and specific
conductivity signals correspond to one another and can be used
interchangeably to control aeration. When the pH in the reactor
decreases to meet the pH setpoint, the ammonium concentration and
specific conductivity decrease as well.
[0104] FIG. 18 shows an example of the method described in FIG. 14
wherein pH controls gas flow rate setpoint which controls gas valve
position. The figure shows the response of the controller to a
disturbance created by a change in the influent flow rate which
corresponds to a change in influent ammonia and alkalinity loading.
The controller adjusts the gas flow setpoint in order to maintain
the pH setpoint.
[0105] FIG. 19 shows that the pH, ammonium, and specific
conductivity signals correspond to one another and can be used
interchangeably to control aeration. When the influent flow rate
decreases the pH controller decreases the gas flow to maintain the
pH setpoint and the ammonium concentration and specific
conductivity also stay constant.
[0106] FIG. 20 shows a cross-sectional view of an example of an
alkalinity-based control system 100'''''' for treating ammonium
containing water in a deammonification MBBR process in which
partial nitritation and anaerobic ammonium oxidation occur
simultaneously, constructed according to the principles of the
disclosure. The system 100'''''' comprises the reactor 17 with the
air diffusers 14, meter 10, control valve 11, alkalinity sensor 23,
and DO sensor 15. Biofilm carriers 12 may be kept in suspension by
continuous aeration provided by the diffusers 14. The influent flow
to the reactor may be equal to the effluent flow and the reactor
may be completely mixed. Sensors 23 and 15 may be located in the
reactor or in the effluent. Gas flow to the reactor may be
determined by the control valve 11. The meter 10 may be located
upstream of the control valve 11 and configured to provide gas flow
rate feedback to the controller 13. A signal from the alkalinity
sensor 23 may provide feedback for any of the disclosed alkalinity
aeration control methods described in FIGS. 22-24, with the option
of using the signal from the DO sensor 15 for control.
[0107] FIG. 21 shows a cross-sectional view of an example of an
expanded alkalinity-based control system 100''''''', constructed
according to the principles of the disclosure. The system
100''''''' includes the IFAS reactor 20 with the diffusers 14,
meter 10, control valve 11, alkalinity sensor 23, DO sensor 15,
clarifier 18 and return activated sludge 19. Biofilm carriers 12
may be kept in suspension by continuous aeration provided by the
diffusers 14. The IFAS configuration includes biomass suspended in
the mixed liquor as well as biomass on the plastic biofilm carriers
12. The influent flow to the reactor may be equal to the effluent
flow and the reactor may be completely mixed. Sensors 23 and 15 may
be located in the reactor or in the effluent. Gas flow to the
reactor may be determined by the control valve 11. The meter 10 may
be located upstream of the control valve 11 and configured to
provide gas flow rate feedback to the controller 13. A signal from
the alkalinity sensor 23 may provide feedback for any of the
disclosed alkalinity aeration control methods described in FIGS.
22-24, with the option of using the signal from the DO sensor 15
for control.
[0108] FIG. 22 shows an example of a method of controlling a gas
valve position or a blower output based on alkalinity, according to
the principles of the disclosure. If the alkalinity feedback is
less than the alkalinity setpoint, then the PID controller
decreases the control valve position or blower output to decrease
the volume/rate of gas supplied to the reactor. If the alkalinity
feedback is greater than the alkalinity setpoint, then the PID
controller increases the control valve position or blower output to
increase the volume/rate of gas supplied to the reactor.
[0109] FIG. 23 shows an example of a method controlling a gas flow
rate setpoint based on alkalinity, wherein the gas flow rate
setpoint controls a valve position or a blower output, according to
the principles of the disclosure. If the alkalinity feedback is
less than the alkalinity setpoint, then the PID 1 controller
decreases the gas flow rate setpoint and the PID 2 controller
decreases the control valve position or blower output to decrease
the volume/rate of gas supplied to the reactor. If the alkalinity
feedback is greater than the alkalinity setpoint, then the PID 1
controller increases the gas flow rate setpoint and the PID 2
controller increases the control valve position or blower output to
increase the volume/rate of gas supplied to the reactor.
[0110] FIG. 24 shows an example of a method of controlling a DO
setpoint based on alkalinity, wherein the DO setpoint controls a
gas flow rate setpoint that controls a valve position or a blower
output, according to the principles of the disclosure. If
alkalinity feedback is less than the alkalinity setpoint, then the
PID 1 controller decreases the DO setpoint, the PID 2 controller
decreases the gas flow rate setpoint, and the PID 3 controller
decreases the control valve position or blower output to decrease
the volume/rate of gas supplied to the reactor. If the alkalinity
feedback is greater than the alkalinity setpoint, then the PID 1
controller increases the DO setpoint, the PID 2 controller
increases the gas flow rate setpoint, and the PID 3 controller
increases the control valve position or blower output to increase
the volume/rate of gas supplied to the reactor.
[0111] FIG. 25 shows an example of pH controlling DO setpoint,
controlling airflow setpoint, controlling air flow control valve.
Over the course of 2 months the controller changed the DO setpoint
in response to disturbances caused by changes in centrate flow (aka
influent ammonia and alkalinity load) while maintaining an ammonia
removal rate in the range of 83-92%. Nitrate production remained
below 15% and pH was maintained around the setpoint of 6.7.
[0112] The term "aeration" means the use of compressed air or
purified oxygen or other gas mixture with the intent of
transferring oxygen from the gas phase to the liquid phase. The
terms "air" and "gas" mean any oxygen-containing gas that might be
used.
[0113] The terms "including", "comprising" and variations thereof,
as used in this disclosure, mean "including, but not limited to",
unless expressly specified otherwise. The terms "a", "an", and
"the", as used in this disclosure, means "one or more", unless
expressly specified otherwise.
[0114] A "controller", as used in this disclosure, means any
machine, device, circuit, component, or module, or any system of
machines, devices, circuits, components, modules, or the like,
which are capable of manipulating data according to one or more
instructions, such as, for example, without limitation, a
processor, a microprocessor, a central processing unit, a general
purpose computer, a super computer, a personal computer, a laptop
computer, a palmtop computer, a notebook computer, a desktop
computer, a workstation computer, a server, or the like, or an
array of processors, microprocessors, central processing units,
general purpose computers, super computers, personal computers,
laptop computers, palmtop computers, notebook computers, desktop
computers, workstation computers, servers, or the like.
[0115] A "communication link", as used in this disclosure, means a
wired and/or wireless medium that conveys data or information
between at least two points. The wired or wireless medium may
include, for example, a metallic conductor link, a radio frequency
(RF) communication link, an Infrared (IR) communication link, an
optical communication link, or the like, without limitation. The RF
communication link may include, for example, WiFi, WiMAX, IEEE
802.11, DECT, 0G, 1G, 2G, 3G or 4G cellular standards, Bluetooth,
and the like.
[0116] Devices that are in communication with each other need not
be in continuous communication with each other, unless expressly
specified otherwise. In addition, devices that are in communication
with each other may communicate directly or indirectly through one
or more intermediaries.
[0117] Although process steps, method steps, algorithms, or the
like, may be described in a sequential order, such processes,
methods and algorithms may be configured to work in alternate
orders. In other words, any sequence or order of steps that may be
described does not necessarily indicate a requirement that the
steps be performed in that order. The steps of the processes,
methods or algorithms described herein may be performed in any
order practical. Further, some steps may be performed
simultaneously.
[0118] When a single device or article is described herein, it will
be readily apparent that more than one device or article may be
used in place of a single device or article. Similarly, where more
than one device or article is described herein, it will be readily
apparent that a single device or article may be used in place of
the more than one device or article. The functionality or the
features of a device may be alternatively embodied by one or more
other devices which are not explicitly described as having such
functionality or features.
[0119] While the disclosure has been described in terms of
exemplary embodiments, those skilled in the art will recognize that
the disclosure can be practiced with modifications in the spirit
and scope of the appended claims. These examples are merely
illustrative and are not meant to be an exhaustive list of all
possible designs, embodiments, applications or modifications of the
disclosure.
* * * * *